This invention relates to railroad car manufacture and, more particularly, to a welding method for manufacturing a bottom cover assembly to the pneumatic outlet of a railroad car.
In the manufacture of pneumatic outlet assemblies for a railway hopper car, one problem encountered is in the fabrication of a bottom valve cover assembly for the outlet. Assembly of the cover requires that two or more longitudinal sections be joined together. Typically this is done by welding adjacent sections together, this welding operation including both an internal and an external weld. The sections comprising the bottom valve cover are generally tubular in shape. Consequently, forming the cover may be thought of as joining together sections of pipe. As is well known in the art, it is sometimes necessary during a welding operation to use inserts in the form of gaskets, for example. The inserts, in turn, may be either wholly or partially consumable.
Most consumable, or partially consumable, inserts are used in joining pipe where welding access to the inside of the pipe is extremely difficult. Examples of welding inserts are shown, for example, in U.S. Pat. Nos. 4,611,830, and 4,652,019. Inserts like those shown in these patents are used to minimize obstructions on the inside surface of a pipe. Here, obstructions are harmful in two ways. First, obstructions inhibit the efficient discharge of lading from a hopper car. Second, obstructions can cause some lading to be retained within the outlet. This lading can then contaminate subsequent ladings shipped in the same car. For certain ladings, any contamination essentially ruins the value of the lading. Hence, there may be a significant economic impact to the owner or lessor of the car resulting from the construction of the cover assembly.
Again with respect to inserts, while they are formed to minimize obstructions on the inside surface of a pipe, it is extremely difficult to achieve a substantially perfectly smooth inner surface at the weld joint between sections. The present invention involves a method of utilizing a fully consumable welding filler metal insert. The method includes use of the insert where welding access to the inside surface of the parts to be joined is limited but not fully obstructed. In these circumstances, access by a TIG welding torch to the inside of the weld joint is possible. However, access to the inside of the joint by a MIG welding torch, and the conventional filler wire fed thereto, is severely limited.